Rack



Feb. 22, 1938; v r F, A, WALES I 2,108,978.

RACK

Filed Nov. 29, 1935 INVENTOR. F 5 n alea ATTORNEYS.

Patented Feb. 22, 1938 UNITED STATES" PATENT OFFICE RACK Fred A. Wales, Detroit, Mich. Application November 29, 1935, Serial No. 5 2,047

' 8 Claims. (01. 204-5);

,This invention relates to racks having holders or clamps adapted to hold articles, such, for example, as pistons, in an electrolytic or other treating bath, the rack also providing an electrical contact between the article and a source of electrical energy. In one embodiment of the invention here shown by way of example, the clamp or holder is adapted for use in a process for forming a protective coating on an aluminum or aluminum alloy piston.

The holders or clamps now in use on racks are generally formed withprojections which fit into one of the piston ring grooves and clamp the piston between them, the only electrical contact being through such points. Inasmuch as the protective coating forms first and to the greatest extent at the points ofelectrical contact, it will be seen that the removal of such clamps of the prior art is accompanied by a stripping of the coating from the surfaces where the clamp and the piston are'in physical contact with each other.

Another disadvantage of these racks is that when the racks are used, for example, in the formation of the so-called oxide coatings on aluminum or its alloys, the electrolyte seeps in between the clamps or holders and the piston,

and as the process continues a very dielectric coating is formed between the support and the object at the point where a good electrical contact is desired. After some use, the clamps acquire an accumulation of dielectric coating particles which-render the clamps less eflicient in making good electrical contacts with the piston. This necessitates the removal of the coating par ticles from the clamp by means of suitable acid or cleaning baths after each, use of the support. The constant cleaning or removal of the accumulated coating particles eventually destroys the clamps and thus greatly increases the costs of the process and equipment.

It is a further characteristic of such racks heretofore known that no provision is made to insure adequate drainage of the electrolyte from the articles when the racks are removed at the conclusion of the processing of the'articles.

An important object of this invention is to provide a rack or support for treating pistons or other articles by submersion in an electrolyte while subjecting the articles to a flow of electrical current therethrough.

It is a further object of the present invention to provide a rack or support in which the elec-itrical contact between the article and the rack is at a point removed from the wearing surface of the article. If any of the formed coating is removed or-' the coating film is broken upon removal of the article from the rack, there will be no break of. the coating at a point where wear occurs.

Another object of the present invention is to provide a rack for articles to be treated by an electrical current flow through an electrolyte, in whichthe electrical contact between the rack and the articles is efiected by a member which 10 is tightly pressed against the article'to form a seal through which no electrolyte can leak and so there is no danger of depositing a coating between the contact points, which in certain instances are dielectric in character.

, Another object of this invention is to-provide a rack for articles to be treated in an electrolytic bath, which provides an electrical contact which is self-cleaning upon connection with the article and establishes a good electrical connection therewith even though the article or the contact member or both may have a film or coating which must'be broken ofi and contact established as the. support is being placed on the piston.

Another object of the present invention is toprovide a rack having article-supporting clamps which are covered with a protective insulating coating to therebyreduce the electrolytic action which occurs between an uninsulated support. v and the electrolyte and thus to lessen contamina- 3 tion in the electrolytic bath due to reactions between the steel forming the supports and the acid electrolyte. 1

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawing forming a part of this specification wherein like reference characters designate correspond-' ing parts in the several views.

Fig. 1 is a perspective view of a preferred form 40 of the support or clamps embodying the present invention. 1

Fig. 2 is a. section through a treating tank-con- -taining electrolyte, showing .a rack having, a

number of pistons mounted thereon.

Fig. 3 is a longitudinal section through the support or clamp, showing a piston held therein. Fig. 4 is a fragmentary view showing a modified form of electrical contact member for use with supports or clamps of the present invention, and is adapted particularly for use where the electrical contact is to be effected on the surface of the article to be held therein.

Before explaining in detailthe present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is notintended to limit the invention claimed herein beyond the requirements of the prior art.

A rack of the present invention comprises a spine or supporting member (Fig. 2), to which a plurality of racks or supports II are secured.

The spine I ll is electrically connected with a bus bar 2 and is suspended downwardly therefrom into the electrolyte |3 in the treating tank I4. The bus bar I2 is electrically insulated from the tank I4 and is supported on blocks l5 of dielec- -tric material, such as hard rubber, Bakelite, or

the like. The rack can be used in various types of operations and may be electrically connected in any manner required by such operations.

Each of the supports or clamps consists of three main parts, a rod 20, a block of insulating material 2| and a U-shaped member 22 forming arms 23 and 24. The rod 20 is screw threaded through a hole in the center of the block 2| of insulating material which is disposed between the arms '23 and 24 and serves to electrically insulate the arms from the rod. The arms 23 and 24 are formed preferably of a single piece of steel or resilient metal strap forming-the member 22, which is then bent into the shape of a V with a flat bottom. The block 2| fits into the bottom of the V and is secured to, the arms 23 and 24 by means of rivets 25 or other suitable fastening means. The member 22 is provided with an opening 26 in the center of the bottom of the V, which is so placed as to register with the opening in the block 2| of insulating material but is sufliciently larger than the hole in the block so that the member 22 is not in electrical contact with the rod 20.

The arms 23 and 24 of the V-shaped metal strip extend out from the block 2| 'at approximately equal angles to the rod 20 which extends between them. The arms 23 and 24 terminate in inwardly directed projections 21 and 28 formed by'sharply bending, the ends of the legs towards each other. and 28 are formed to engage with a selected part of an article to be held therein. As here shown,

the ends are tapered in elevation and are concave in plan view so that they will fit into piston ring grooves 29 on the head of a piston 30. The

' arms 23 and 24 are spaced so as to engage a piston 30 on opposed sides thereof and to clamp the piston tightly between them when the threaded rod 20 is screwed into engagement with the head of the piston and pressure is applied thereto. The end of the threaded rod 20 at the point of engagement with the piston may be formed with a conical point 32 which is adapted to fit into a pilot hole 33 in the head of the piston, if such a hole is present therein. If, however, the piston is not provided with the pilot hole 33, the rod 2| is provided witha spherical end 34 (Fig. 4) which forms -a point contact with the surface of the head of the piston 35.

The spine or supporting member Ill of the rack of the present invention is provided with a series of extensions 40 which are drilled and tapped to provide a screw-threaded engagement with the ends 5f the rods. As shown ifi'Fig. 2, such extensions provide for an 'angularly depending The ends of these projections 21 connection with the rods 20. "Such an arrangement provides for the maximum number of supports or clamps II in a given space. This arrangement also permits suspension of the articles to be treated in the bath in such a manner a that upon removal of the rack and articles from the bath, a thorough draining of the liquid electrolyte is insured. Thus the rack of the present 1 invention may be used, not only to hold the articonnection between the spine Ill and the arms 23 and 24. A look nut 4| is provided on the rods 20 and is adapted to engage a face of the extensions 40 and thus to secure the clamps or supports against unintended detachment from the spine ID.

A protective coating 42,preferably of rubber, Bakelite or other dielectric and acid-resisting material, is placed on the arms 23 and 24 and prevents contamination of the electrolyte by reactions which otherwise wuuld occur between the electrolyte and the material in the arms 23 and 24. screw threaded throughout their lengths and exposed to the electrolyte, or they may be covered with a protective dielectric and acid-resisting coating for a portion of their lengths and be screw threaded for a predetermined distance adjacent the blocks 2|. Such modifications, being within the purview of one skilled in the art, are hereby deemed included as a part of the present invention.

Assuming that the rackis to be used for th treatment of pistons in an electrolyte, the operation of the present invention is as follows: The piston 3|l is pressed between the ends 21 and 28 of the arms 23 and 24, with the projections on the ends of the arms fitting into opposite sides of one of the piston ring grooves 29. The arms 23 and 24, the insulating block 2|, and the piston are then screwed as a unit on the threaded rod 20 until the conical end 32 of the rod'20 enters into and is firmly seated in the pilot hole 33 in the head of the piston. As the piston is being screwed up tightly onto the end of the threaded rod, any coating which might have been depos-- ited on the conical end of the rodduring pre- ,vious use, is broken by the rubbing of the walls of the pilot hole on the end of the rod, direct metal to metal, so that an electrical contact is formed. When the piston is screwed up tightly, the end of the rod is held in the pilot hole with considerable pressure, so that no electrolyte can leak in between it and the piston and deposit a coating on the end of the rod which may, in some instances, interfere with the electrical contact between the rod and thepiston.

If the-article to be treated does not have a pilot hole, as is the case with pistons finished iii a centerless grinder for example, a spherical end is provided on the rod 20 so that when the piston is screwed into engagement with it, a point contact is established with the head of the piston. The pressure of. the contact between the rod and the piston is very substantial so that a tight contact is secured which prevents to a large degree the seepage of any electrolyte between the end of the rod and the piston, so that It is thus seen that the area of contact between Therods 2| may be, as here shown,'

the support and the piston, which serves to contact electricity between them, is protected from the action of the electrolyte and is also a selfcleaning contact. Inasmuch as no coating or plating is formed at the point of electrical contact and this point is not on an exposed bearing surface, very beneficial results are attained over known devices wherein the electrical contact may be through arms or other members which contact with a portion of the exposed bearing surface. Such feature is of particular advantage when the rack of. the present invention is used in processes for forming a coating, such as the so-called anodic or oxide coating, on pistons formed of aluminum or aluminum base alloys.

Such coatings are very hard and tend to be brittle so that upon even a slight break in the exposed bearing surface, there is a tendency for the coatings to flake or peel off the metal. Such coatings have dielectric properties and form at thepoint of electrical flow through the electrolyte. The direct and self-sealing electrical contacts resulting from the use of the racks of thepresent invention, therefore prevent power loss and make for more efllcient operation of such processes as the electrical connection is protected throughout the operation.

I claim:

1. A holder for supporting pistons in an electrolytic bath and comprising a block of dielectric material, a pair of diverging arms extending from ,said block, the ends of the armsbeing adapted to engage with the piston ring grooves in the head of a piston placed between the said arms, an

extensible member extending between the arms and in screw-threaded engagement with the said block and having a point contacting with the head of the piston.

2. A holder for supporting pistons in an electrolytic bath and comprising a block of dielectric material, a pair of diverging arms extending from said block, the ends of the arms being formed to flt into opposite sides of. one of the piston ring grooves adjacent the top of a piston placed between the arms, an electrically conductive member extending between the arms and through said block and adapted to establish and maintain an electrical contact with the top of the piston.

3. A holder for supporting pistons in an electrolytic bath and comprising a threaded electrically conductive rod having a conical point, a block of insulating material having a screwthreaded hole through which said rod is screw threaded, a metal strap secured to said block and formed to provide a pair of diverging arms extending outwardly from said block and on opposite sides of said rod, the ends of said arms being bent on a line substantially perpendicular to the rod to form members adapted to enter one of the piston ring grooves of a piston coaxial with the rod and to securely hold the piston between said rod and said ends.

4. A rack for suspending an article in a treating bath and comprising a spine, article-holding members secured to said spine and depending downwardly and outwardly therefrom at an angle to the center line of said spine, said articleholding members comprising arms, and an electrically conductive pressure member associated therewith but electrically insulated therefrom, said pressure member comprising a screwthreaded rod secured to said spine and electrically connected therewith, and having a portion on the end thereof adapted to establish an electrical contact with an article held by said arms.

5. A rack for suspending an article in a treating bath and comprising a spine, article-holding members secured to said spine and depending downwardly and outwardly therefrom at an angle to the center line of said spine, said article-holding members comprising arms having a. protective covering of a dielectric and acid-resistin material, and an electrically conductive pressure member associated therewith but electrically insulated therefrom, said pressure member comprising a screw-threaded rod secured to said spine and electrically connected therewith, and having a portion on the end thereof adapted to establish an electrical contact with an article held by said arms.

6. A rack adapted for use in electrolytic treating processes and comprising a spine arranged for electrical connection with a source of electrical energy, a plurality of. clamps carried by said spine, each clamp comprising an electrically conductive member attached to said spine and extending therefrom to a point of electrical contact with an article to be treated, and arms associated with but electrically insulated from said member and adapted to cooperate with said member to hold the article to be treated in electrical contact with said member.

'7. A rack adapted for use in electrolytic treating processes and comprising a spine arranged for electrical connection with a source of electrical energy, a plurality of clamps carried by said spine, each clamp comprising an electrically conductive member attached to said spine and extending therefrom to a point of electrical contact with an article to be treated, arms associated with but electrically insulated from said member and adapted to cooperate with said member to hold the article to be treated in electrical contact with said member, and a protective covering secured to said arms to prevent a reaction between the electrolyte and the material in said arms.

'8. A holder for supporting pistons in an electrolytic bath and comprising a block of dielectric material, a pair of diverging arms extending from said block and covered with a protective covering substantially inert in the electrolytic bath, the ends of the arms being formed to fit into opposite sides of one of the piston ring grooves adjacent the top of a piston electrically conductive member extending between the arms and through said block and adapted to establish and maintain an electrical contact with the top of the piston.

FRED A. WALK.

placed between the arms, an 

